Band discontinuities at epitaxial SrTiO3/Si(001) heterojunctions

We have used photoemission methods to directly measure the valence and conduction band offsets at ${\mathrm{SrTiO}}_3/\mathrm{Si(001)}$ interfaces, as prepared by molecular-beam epitaxy. Within experimental error, the measured values are the same for growth on n- and $p\mathrm{-Si},$ with the entire band discontinuity occurring at the valence band edge. In addition, band bending is much larger at the $p\mathrm{-Si}$ heterojunction than at the n-type heterojunction. Previously published threshold voltage behavior for these interfaces can now be understood in light of the present results.